1. Field of the Invention
The present invention relates to an electronic control device for automotive use which utilizes a plurality of microprocessors to perform engine control and other vehicle control.
2. Description of Related Art
Along with recent diversification and growth in complexity of control, a need has appeared for a plurality of microprocessors in an electronic control unit for vehicle use, and technology has been developed to perform data communication among the various microprocessors. Additionally, technology which can standardize microprocessors for use even with different vehicle models and changes in specifications is also desired from the standpoint of lower cost.
In this regard, a control device of an engine for vehicle use is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 61-16250 as an example of of microprocessors. With this control device, specific data for each specification which corresponds to change in specifications is previously stored in a ROM of a first microprocessor, and standard data with no change in specifications is previously stored in a ROM of a second microprocessor. Accordingly, at a time of initialization, the contents of data (i.e., a control map) stored in the ROM of the first microprocessor is sent to the second microprocessor, and along with this, the memory settings for the microprocessor are made, and the second microprocessor executes control on the basis of the control map in RAM at that time, i.e, the map data which has been stored in the first microprocessor. Standardization of the second microprocessor can be achieved in such cases.
However, the problem described below occurs in such prior art control devices. Namely, in the foregoing device, data communication from the first microprocessor to the second microprocessor is performed only during initialization. For this reason, problems such as operation of the second microprocessor with incorrect control data or failure of control of the second microprocessor to start may occur in a case where communication during initialization is not performed correctly.
Additionally, in a case of a microprocessor installed on a vehicle, control data within RAM may be destroyed by usage under poor conditions (high temperature or high humidity) or by occurrence of noise due to drive pulses of the ignition system or the like, making it impossible to perform normal operation.